From 85b0ae854f6958c6c6815fdfd3d14cd052ee805a Mon Sep 17 00:00:00 2001
From: Hsiao-Wei Wang <hsiaowei.eth@gmail.com>
Date: Thu, 27 Jul 2023 23:12:49 +0800
Subject: [PATCH] handle `len(blobs) == 0` case

---
 tests/core/pyspec/eth2spec/test/helpers/fork_choice.py | 10 ++++++----
 tests/formats/fork_choice/README.md                    |  3 ++-
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/tests/core/pyspec/eth2spec/test/helpers/fork_choice.py b/tests/core/pyspec/eth2spec/test/helpers/fork_choice.py
index c3f496a49..a6babefd3 100644
--- a/tests/core/pyspec/eth2spec/test/helpers/fork_choice.py
+++ b/tests/core/pyspec/eth2spec/test/helpers/fork_choice.py
@@ -173,10 +173,12 @@ def add_block(spec,
 
     # Check blob_data
     if blob_data is not None:
-        assert len(blob_data.blobs) == len(blob_data.proofs)
         blobs = spec.List[spec.Blob, spec.MAX_BLOBS_PER_BLOCK](blob_data.blobs)
-        blobs_root = blobs.hash_tree_root()
-        yield get_blobs_file_name(blobs_root=blobs_root), blobs
+        if len(blobs) > 0:
+            blobs_root = blobs.hash_tree_root()
+            yield get_blobs_file_name(blobs_root=blobs_root), blobs
+        else:
+            blobs_root = None
 
     is_blob_data_test = blob_data is not None
 
@@ -184,7 +186,7 @@ def add_block(spec,
         if is_blob_data_test:
             test_steps.append({
                 'block': get_block_file_name(signed_block),
-                'blobs': get_blobs_file_name(blobs_root=blobs_root),
+                'blobs': None if blobs_root is None else get_blobs_file_name(blobs_root=blobs_root),
                 'proofs': [encode_hex(proof) for proof in blob_data.proofs],
                 'valid': valid,
             })
diff --git a/tests/formats/fork_choice/README.md b/tests/formats/fork_choice/README.md
index bfc8a423d..4347e95f2 100644
--- a/tests/formats/fork_choice/README.md
+++ b/tests/formats/fork_choice/README.md
@@ -85,8 +85,9 @@ The parameter that is required for executing `on_block(store, block)`.
 {
     block: string           -- the name of the `block_<32-byte-root>.ssz_snappy` file.
                               To execute `on_block(store, block)` with the given attestation.
-    blobs: string           -- optional, the name of the `blobs_<32-byte-root>.ssz_snappy` file.
+    blobs: string or `null` -- optional, the name of the `blobs_<32-byte-root>.ssz_snappy` file.
                                The blobs file content is a `List[Blob, MAX_BLOBS_PER_BLOCK]` SSZ object.
+                               If it's `null`, `blobs` is an empty list.
     proofs: array of byte48 hex string -- optional, the proofs of blob commitments.
     valid: bool             -- optional, default to `true`.
                                If it's `false`, this execution step is expected to be invalid.